The city that Amy and Dan have gone to in this book:

Paris, France. Dan and Amy have now started the hunt for the clues, but so have many other people. [AP]

Clues from this book:

1. Richard S???????
2. Gold, Zinc, Water



Amy and Dan are being chased through Paris, France after the first clue by the Kabras into an underground bone maze. (G.S.) Their first mission EVER! They choose the dangerous path. (M.B.)

I wonder why they got chased when they were doing their mission.